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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Geodetic studies by laser ranging to satellites.

For three months in 1970, two Goddard Space Flight Center (GSFC) laser tracking systems were used to try to detect the motion of the pole of rotation of the earth. More than two hundred passes of the Beacon Explorer C spacecraft were observed as it passed between the two stations, and these data were used to determine the orbital inclination of the spacecraft. The analysis required the accurate determination of the relative positions of the two tracking stations and the identification of the perturbations to the spacecraft orbit, in particular, those due to the gravitational fields of the earth, sun, and moon and those caused by the solid-earth tides. The results to date indicate that the GSFC laser systems can determine interstation distances with a repeatability of about 25 cm and that a new value of the Love number k that represents the distortion of the earth's gravity field caused by the tidal deformation of the earth is 0.35 plus or minus 0.05.

Smith, D. E.↗
NASA NTRS1972

Measured physical and optical properties of the passive geodetic satellite /Pageos/ and Echo 1.

Two satellites used for geodesy, Pageos and Echo 1, have been observed in a continuing program since 1966 to determine the stability of their physical and optical properties. Measurements are made in the UBVRI spectral system. The amount of solar radiation reflected from a satellite's surface is measured photoelectrically and is calibrated against known stellar magnitudes by standard astronomical techniques. The calibrated satellite magnitudes are analyzed with respect to the sun-satellite-observer phase angle to infer the shape and size of the satellite and the reflective properties of the satellite's surface material. The physical and optical properties are used to determine proper position of the solar image on the satellite's surface, resulting in more precise geometric geodesy. Quantitative results from five observing periods indicate that, although local structural anomalies appear to exist, both satellites essentially maintained their nominal average 30.48-meter (50-ft) radius of curvature and specular reflecting characteristics.

Mcdougal, D. S.↗
NASA NTRS1974

Basic research and data analysis for the National Geodetic Satellite Program and for the Earth and Ocean Physics Application Program

Accomplishments in the continuing programs are reported. The data were obtained in support of the following broad objectives: (1) to provide a precise and accurate geometric description of the earth's surface; (2) to provide a precise and accurate mathematical description of the earth's gravitational field; and (3) to determine time variations of the geometry of the ocean surface, the solid earth, the gravity field, and other geophysical parameters.

Source record↗
NASA NTRS1973

Engineering studies related to geodetic and oceanographic remote sensing using short pulsed techniques

Theoretical basis is presented for a feasibility study of measuring global ocean surface current pattern from satellites and aircraft. The analysis is supported by some preliminary laboratory experiments. Since the ultimate goal is to establish an operational routine for monitoring the global current pattern, a nondisturbing remote sensing device using a laser probe was developed. Detailed construction of the measuring system and the results of some preliminary observations are also presented.

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NASA NTRS1974

Geodetic and dynamical properties of planets

Data concerning planetary dynamics and geodesy are severely limited because, at present, only one planetary system in the universe can be studied. It is, therefore, impossible to base the study of planets on a significant statistical sample. The gravity fields of the planets are discussed, giving attention to the various space missions involved in the collection of the relevant data. Other subjects considered include planetary shape and topography, planetary rotations, and planetary interiors. The basic problem in finding an acceptable model for the planetary interior is to specify the chemical composition with depth and then to find a physically realistic equation for the material.

Anderson, J. D.↗
NASA NTRS1974

Geodetic results from ISAGEX data

Laser and camera data taken during the International Satellite Geodesy Experiment (ISAGEX) were used in dynamical solutions to obtain center-of-mass coordinates for the Astro-Soviet camera sites at Helwan, Egypt, and Oulan Bator, Mongolia, as well as the East European camera sites at Potsdam, German Democratic Republic, and Ondrejov, Czechoslovakia. The results are accurate to about 20m in each coordinate. The orbit of PEOLE (i=15) was also determined from ISAGEX data. Mean Kepler elements suitable for geodynamic investigations are presented.

Marsh, J. G.↗